Pub Date : 2025-10-28DOI: 10.1016/j.euromechflu.2025.204398
Shuo Peng, Qian Chen
The turbulent/non-turbulent interface (TNTI) is a thin layer with a steep gradient of vorticity magnitude that separates turbulent from irrotational fluids in turbulent shear flows. The interface plays a crucial role in the exchange of mass, momentum and energy and scalars between the two sides, as the properties of the fluids on either side differ significantly. Consequently, accurately detecting the TNTI is essential for the study of related physical phenomena. Currently, various methods for TNTI detection have been developed. This paper provides a comprehensive review of the primary TNTI detection methods, beginning with three typical methods based on vorticity, passive scalars, and turbulent kinetic energy. These methods are thoroughly analyzed in terms of their detection mechanisms, detection threshold selection criteria, and overall performance in diverse flow environments. Furthermore, the paper explores innovative methods that have been developed in recent years, such as machine learning approaches, the homogeneity criterion, and virtual particle tracking methods. Finally, the paper synthesizes the strengths and limitations of these TNTI detection methods and offers insights into future research on the detection of the TNTI.
{"title":"Turbulent/non-turbulent interface detection methods for turbulent shear flows","authors":"Shuo Peng, Qian Chen","doi":"10.1016/j.euromechflu.2025.204398","DOIUrl":"10.1016/j.euromechflu.2025.204398","url":null,"abstract":"<div><div>The turbulent/non-turbulent interface (TNTI) is a thin layer with a steep gradient of vorticity magnitude that separates turbulent from irrotational fluids in turbulent shear flows. The interface plays a crucial role in the exchange of mass, momentum and energy and scalars between the two sides, as the properties of the fluids on either side differ significantly. Consequently, accurately detecting the TNTI is essential for the study of related physical phenomena. Currently, various methods for TNTI detection have been developed. This paper provides a comprehensive review of the primary TNTI detection methods, beginning with three typical methods based on vorticity, passive scalars, and turbulent kinetic energy. These methods are thoroughly analyzed in terms of their detection mechanisms, detection threshold selection criteria, and overall performance in diverse flow environments. Furthermore, the paper explores innovative methods that have been developed in recent years, such as machine learning approaches, the homogeneity criterion, and virtual particle tracking methods. Finally, the paper synthesizes the strengths and limitations of these TNTI detection methods and offers insights into future research on the detection of the TNTI.</div></div>","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":"116 ","pages":"Article 204398"},"PeriodicalIF":2.5,"publicationDate":"2025-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145464113","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-23DOI: 10.1016/j.euromechflu.2025.204399
Nayab , Taqi Ahmad Cheema , Naveed Razzaq Butt , Atif Muzaffar , Rizwan Ullah
Gravitational vortex systems (GVS) are defined as systems that leverage gravitational vortices for applications such as energy generation and heat transfer in basins free from obstructions. These basins are commonly of two types: cylindrical and conical. Under the given flow conditions, fluid properties, and geometric dimensions of the basin, the vortex rises to a certain height, termed as the vortex head, which is the most crucial parameter for designing these systems. However, the absence of predictive tools for vortex head often leads to basin designs that fail to form a proper vortex head, causing overflow or turbine submergence in vortex powerplants, or uneven heating in vortex basins used for heat exchangers. Traditional methods regulate the flowrate to control the vortex head in vortex basins, but this approach compromises the strength of the vortex. To address this, an empirical framework has been developed to predict the vortex head based on flow conditions, fluid properties, and basin geometry. The correlation includes four dimensionless numbers: the orifice-to-basin diameter ratio (d/D), a geometric-to-flow parameters ratio, a vortex strength number (VN), and free stream turbulence (FST). The applicability of the model is limited to cylindrical and conical basins without internal obstructions, for diameter ratios up to d/D ≤ 0.18, and with water used as the only working fluid. Statistical evaluation of the model shows a high degree of accuracy, with a coefficient of determination (R2) of 0.942, root means square error (RMSE) of 0.073 and mean average error (MAE) of 0.054. Residual error analysis confirms the consistency and reliability of the predictions. The model estimates vortex head within a ± 20 % tolerance and offers a practical design tool for laboratory-scale setups and industrial-scale gravitational vortex applications.
{"title":"Development of a novel empirical correlation for vortex head in gravitational water vortex","authors":"Nayab , Taqi Ahmad Cheema , Naveed Razzaq Butt , Atif Muzaffar , Rizwan Ullah","doi":"10.1016/j.euromechflu.2025.204399","DOIUrl":"10.1016/j.euromechflu.2025.204399","url":null,"abstract":"<div><div>Gravitational vortex systems (GVS) are defined as systems that leverage gravitational vortices for applications such as energy generation and heat transfer in basins free from obstructions. These basins are commonly of two types: cylindrical and conical. Under the given flow conditions, fluid properties, and geometric dimensions of the basin, the vortex rises to a certain height, termed as the vortex head, which is the most crucial parameter for designing these systems. However, the absence of predictive tools for vortex head often leads to basin designs that fail to form a proper vortex head, causing overflow or turbine submergence in vortex powerplants, or uneven heating in vortex basins used for heat exchangers. Traditional methods regulate the flowrate to control the vortex head in vortex basins, but this approach compromises the strength of the vortex. To address this, an empirical framework has been developed to predict the vortex head based on flow conditions, fluid properties, and basin geometry. The correlation includes four dimensionless numbers: the orifice-to-basin diameter ratio (d/D), a geometric-to-flow parameters ratio, a vortex strength number (V<sub>N</sub>), and free stream turbulence (FST). The applicability of the model is limited to cylindrical and conical basins without internal obstructions, for diameter ratios up to d/D ≤ 0.18, and with water used as the only working fluid. Statistical evaluation of the model shows a high degree of accuracy, with a coefficient of determination (R<sup>2</sup>) of 0.942, root means square error (RMSE) of 0.073 and mean average error (MAE) of 0.054. Residual error analysis confirms the consistency and reliability of the predictions. The model estimates vortex head within a ± 20 % tolerance and offers a practical design tool for laboratory-scale setups and industrial-scale gravitational vortex applications.</div></div>","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":"116 ","pages":"Article 204399"},"PeriodicalIF":2.5,"publicationDate":"2025-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145414862","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-20DOI: 10.1016/j.euromechflu.2025.204396
Sepideh Salimi, Hamid Sadat
High-fidelity simulations are conducted to analyze physiological flows in non-planar curved artery models using physiological flow rates under pulsatile flow conditions. Additional simulations are performed under steady flow conditions at various Reynolds numbers, as well as for planar curved models for comparison. The results indicate that the torsion-induced effects are more pronounced under pulsatile flow than in steady conditions. During the acceleration phase, streamwise velocity peaks near the outer-upper wall close to the inlet and gradually shifts toward the outer-lower wall downstream, reinforcing asymmetric centrifugal effects. As flow transitions to deceleration, the streamwise velocity weakens, but the secondary flows intensify, further highlighting the influence of torsion. These asymmetric secondary flows lead to pronounced differences between the upper and lower deformed Dean (DD) vortices, with the lower DD vortex typically becoming larger and more persistent. Torsion also alters the trajectory and strength of deformed Lyne (DL) and split-Dean (SD) vortices, resulting in earlier vortex splitting and more complex interactions along the pipe, including asymmetric merging between upper and lower structures. Furthermore, torsion alters the wall shear stress (WSS) patterns, leading to asymmetric WSS distributions with localized regions of elevated and reduced WSS on the upper and lower walls, along with high oscillatory behavior throughout the cardiac cycle.
采用脉动流条件下的生理流速，对非平面弯曲动脉模型进行了高保真模拟。在不同雷诺数的稳定流动条件下进行了额外的模拟，并对平面弯曲模型进行了比较。结果表明，在脉动工况下，扭转效应比稳定工况下更为明显。在加速阶段，沿流速度在靠近进气道的外上壁附近达到峰值，并逐渐向下游的外下壁移动，增强了非对称离心效应。当气流向减速过渡时，向流速度减弱，但二次流加剧，进一步凸显了扭转的影响。这些不对称的二次流导致了上下形变迪安（DD）涡之间的显著差异，下形变迪安（DD）涡通常变得更大、更持久。扭转还会改变变形Lyne （DL）和分裂- dean （SD）涡流的轨迹和强度，导致涡流分裂更早，以及管道沿线更复杂的相互作用，包括上下结构之间的不对称合并。此外，扭转改变了壁面剪切应力（WSS）模式，导致壁面剪切应力分布不对称，在上下壁面局部区域WSS升高或降低，并在整个心脏周期中具有高振荡行为。
{"title":"Dynamics of physiological blood flow in non-planar curved artery models","authors":"Sepideh Salimi, Hamid Sadat","doi":"10.1016/j.euromechflu.2025.204396","DOIUrl":"10.1016/j.euromechflu.2025.204396","url":null,"abstract":"<div><div>High-fidelity simulations are conducted to analyze physiological flows in non-planar curved artery models using physiological flow rates under pulsatile flow conditions. Additional simulations are performed under steady flow conditions at various Reynolds numbers, as well as for planar curved models for comparison. The results indicate that the torsion-induced effects are more pronounced under pulsatile flow than in steady conditions. During the acceleration phase, streamwise velocity peaks near the outer-upper wall close to the inlet and gradually shifts toward the outer-lower wall downstream, reinforcing asymmetric centrifugal effects. As flow transitions to deceleration, the streamwise velocity weakens, but the secondary flows intensify, further highlighting the influence of torsion. These asymmetric secondary flows lead to pronounced differences between the upper and lower deformed Dean (DD) vortices, with the lower DD vortex typically becoming larger and more persistent. Torsion also alters the trajectory and strength of deformed Lyne (DL) and split-Dean (SD) vortices, resulting in earlier vortex splitting and more complex interactions along the pipe, including asymmetric merging between upper and lower structures. Furthermore, torsion alters the wall shear stress (WSS) patterns, leading to asymmetric WSS distributions with localized regions of elevated and reduced WSS on the upper and lower walls, along with high oscillatory behavior throughout the cardiac cycle.</div></div>","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":"116 ","pages":"Article 204396"},"PeriodicalIF":2.5,"publicationDate":"2025-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145340696","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-18DOI: 10.1016/j.euromechflu.2025.204393
Weiyu Shen , Rodolfo Ostilla-Mónico , Xiaojue Zhu
Solar atmosphere hosts intricate interactions between vortex tubes and magnetic flux, which channel convective energy into the upper atmosphere and shape large-scale magnetic activity. To probe these dynamics in a controlled setting, we perform direct numerical simulations of antiparallel vortex tubes embedded with magnetic flux tubes, varying the interaction parameter that measures the Lorentz–inertial balance. High-resolution visualizations uncover distinct regimes of coupled evolution, including vortex-dominated reconnection, Lorentz-suppressed reconnection, instability-triggered cascades, and Lorentz-induced vortex disruption. The rendered structures highlight not only the physical transitions but also the striking morphologies, ranging from braided filaments to spiralized cores, that emerge as magnetic intensity strengthens. These findings show how Lorentz–inertial balance regulates reconnection, instability, and energy transfer in magnetohydrodynamic flows.
{"title":"Vortices vs. magnetic fields: Competing orders in flux tubes","authors":"Weiyu Shen , Rodolfo Ostilla-Mónico , Xiaojue Zhu","doi":"10.1016/j.euromechflu.2025.204393","DOIUrl":"10.1016/j.euromechflu.2025.204393","url":null,"abstract":"<div><div>Solar atmosphere hosts intricate interactions between vortex tubes and magnetic flux, which channel convective energy into the upper atmosphere and shape large-scale magnetic activity. To probe these dynamics in a controlled setting, we perform direct numerical simulations of antiparallel vortex tubes embedded with magnetic flux tubes, varying the interaction parameter <span><math><msub><mrow><mi>N</mi></mrow><mrow><mi>i</mi></mrow></msub></math></span> that measures the Lorentz–inertial balance. High-resolution visualizations uncover distinct regimes of coupled evolution, including vortex-dominated reconnection, Lorentz-suppressed reconnection, instability-triggered cascades, and Lorentz-induced vortex disruption. The rendered structures highlight not only the physical transitions but also the striking morphologies, ranging from braided filaments to spiralized cores, that emerge as magnetic intensity strengthens. These findings show how Lorentz–inertial balance regulates reconnection, instability, and energy transfer in magnetohydrodynamic flows.</div></div>","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":"115 ","pages":"Article 204393"},"PeriodicalIF":2.5,"publicationDate":"2025-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145333093","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-14DOI: 10.1016/j.euromechflu.2025.204390
Rajesh Ranjan Dora , Michael H. Meylan , Sanjay Kumar Mohanty
This study investigates wave energy extraction by a floating piezoelectric wave energy converter (PWEC) placed near a wall. The floating PWEC is anchored by mooring lines at its edges to the ocean bottom. This design simulates a potential real-world application of piezoelectric wave energy converters, and the wave-structure interaction is crucial in this arrangement as it influences the superposition of incoming, radiated, and reflected wave components. The coupled hydro-electromechanical equation and dispersion relation for a floating PWEC are derived. The eigenfunction expansion method is then used to investigate the energy extraction by the system. Also, the study examines reflection & dissipation coefficients, the bending moment & shear force of the floating PWEC, and wave force on the wall. Further, the time-dependent modeling of PWEC utilizing a Gaussian pulse is examined, and it is revealed that moored PWEC vibrates for longer times than free PWEC, indicating enhanced energy extraction. Furthermore, it is observed that positioning the PWEC next to a wall, structure, or breakwater can substantially increase energy production. Additionally, the moored PWEC can exhibit efficient damping effects near the wall or structure, making it a multifunctional device.
{"title":"Analysis of a moored floating piezoelectric wave energy converter in the presence of a wall","authors":"Rajesh Ranjan Dora , Michael H. Meylan , Sanjay Kumar Mohanty","doi":"10.1016/j.euromechflu.2025.204390","DOIUrl":"10.1016/j.euromechflu.2025.204390","url":null,"abstract":"<div><div>This study investigates wave energy extraction by a floating piezoelectric wave energy converter (PWEC) placed near a wall. The floating PWEC is anchored by mooring lines at its edges to the ocean bottom. This design simulates a potential real-world application of piezoelectric wave energy converters, and the wave-structure interaction is crucial in this arrangement as it influences the superposition of incoming, radiated, and reflected wave components. The coupled hydro-electromechanical equation and dispersion relation for a floating PWEC are derived. The eigenfunction expansion method is then used to investigate the energy extraction by the system. Also, the study examines reflection & dissipation coefficients, the bending moment & shear force of the floating PWEC, and wave force on the wall. Further, the time-dependent modeling of PWEC utilizing a Gaussian pulse is examined, and it is revealed that moored PWEC vibrates for longer times than free PWEC, indicating enhanced energy extraction. Furthermore, it is observed that positioning the PWEC next to a wall, structure, or breakwater can substantially increase energy production. Additionally, the moored PWEC can exhibit efficient damping effects near the wall or structure, making it a multifunctional device.</div></div>","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":"115 ","pages":"Article 204390"},"PeriodicalIF":2.5,"publicationDate":"2025-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145333094","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-14DOI: 10.1016/j.euromechflu.2025.204389
Nabila Naz
The electrohydrodynamics (EHD) of droplets under electric fields underpins technologies from ink-jet printing and electrosprays to droplet sorting and microfluidics, yet accurate prediction remains challenging because most existing studies are confined to two-dimensional or axisymmetric models and often neglect surface-charge convection, a mechanism that strongly modifies interfacial stresses and breakup. To address this gap, we develop a fully three-dimensional (3D) level-set computational framework for leaky–dielectric two-phase flows that resolves bulk charge conservation, interfacial surface-charge convection, and topology change over a wide range of electric Reynolds numbers (the ratio of charge-relaxation to convection time) and electric capillary numbers (the ratio of electric stress to surface tension). Unlike existing three-dimensional studies that either neglect surface-charge convection or are restricted to small deformations without breakup, our framework provides a comprehensive 3D treatment of finite- charge convection, topology change, and breakup mapping. The method is carefully verified (mass conservation error ) and validated against Taylor’s small-deformation theory and silicone–castor oil experiments, confirming quantitative accuracy. Our simulations demonstrate that surface-charge convection redistributes interfacial charges, weakens EHD circulation, suppresses oblate deformation, and enhances prolate deformation; three-dimensional charge maps and two-dimensional cross-sectional contours quantify these effects in detail. For prolate drops, we capture and classify breakup transitions in full 3D — from end-pinching to conic cusping and ultimately tip streaming — and construct a comprehensive phase diagram. By integrating finite- effects, 3D surface-charge diagnostics, and breakup mapping in a validated computational method, this study establishes a novel predictive framework for electric-field-driven droplet technologies.
{"title":"A three-dimensional level set method for two-phase electrohydrodynamics with finite electric Reynolds number","authors":"Nabila Naz","doi":"10.1016/j.euromechflu.2025.204389","DOIUrl":"10.1016/j.euromechflu.2025.204389","url":null,"abstract":"<div><div>The electrohydrodynamics (EHD) of droplets under electric fields underpins technologies from ink-jet printing and electrosprays to droplet sorting and microfluidics, yet accurate prediction remains challenging because most existing studies are confined to two-dimensional or axisymmetric models and often neglect surface-charge convection, a mechanism that strongly modifies interfacial stresses and breakup. To address this gap, we develop a fully three-dimensional (3D) level-set computational framework for leaky–dielectric two-phase flows that resolves bulk charge conservation, interfacial surface-charge convection, and topology change over a wide range of electric Reynolds numbers <span><math><mrow><mi>R</mi><msub><mrow><mi>e</mi></mrow><mrow><mi>E</mi></mrow></msub></mrow></math></span> (the ratio of charge-relaxation to convection time) and electric capillary numbers <span><math><mrow><mi>C</mi><msub><mrow><mi>a</mi></mrow><mrow><mi>E</mi></mrow></msub></mrow></math></span> (the ratio of electric stress to surface tension). Unlike existing three-dimensional studies that either neglect surface-charge convection or are restricted to small deformations without breakup, our framework provides a comprehensive 3D treatment of finite-<span><math><mrow><mi>R</mi><msub><mrow><mi>e</mi></mrow><mrow><mi>E</mi></mrow></msub></mrow></math></span> charge convection, topology change, and breakup mapping. The method is carefully verified (mass conservation error <span><math><mrow><mo><</mo><mn>0</mn><mo>.</mo><mn>5</mn><mtext>%</mtext></mrow></math></span>) and validated against Taylor’s small-deformation theory and silicone–castor oil experiments, confirming quantitative accuracy. Our simulations demonstrate that surface-charge convection redistributes interfacial charges, weakens EHD circulation, suppresses oblate deformation, and enhances prolate deformation; three-dimensional charge maps and two-dimensional cross-sectional contours quantify these effects in detail. For prolate drops, we capture and classify breakup transitions in full 3D — from end-pinching to conic cusping and ultimately tip streaming — and construct a comprehensive <span><math><mrow><mo>(</mo><mi>C</mi><msub><mrow><mi>a</mi></mrow><mrow><mi>E</mi></mrow></msub><mo>,</mo><mi>R</mi><msub><mrow><mi>e</mi></mrow><mrow><mi>E</mi></mrow></msub><mo>)</mo></mrow></math></span> phase diagram. By integrating finite-<span><math><mrow><mi>R</mi><msub><mrow><mi>e</mi></mrow><mrow><mi>E</mi></mrow></msub></mrow></math></span> effects, 3D surface-charge diagnostics, and breakup mapping in a validated computational method, this study establishes a novel predictive framework for electric-field-driven droplet technologies.</div></div>","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":"115 ","pages":"Article 204389"},"PeriodicalIF":2.5,"publicationDate":"2025-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145333092","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-14DOI: 10.1016/j.euromechflu.2025.204395
Mustafa Turkyilmazoglu , Abdulaziz Alotaibi
Building upon a modified Karman–Pohlhausen technique, a recent study by Panfilov (2021) employed spherical coordinates to solve the heat transport problem in a heterogeneous domain surrounding a cavity storing cryogenic fluids underground. This analysis revealed the formation of an ice ring around the cavity, acting as a protective barrier against flooding from the stored material. This present work expands on that research by introducing heat generation and absorption into the media, aiming to analyze the temporal evolution of temperature and its impact on ice ring formation. Such heat exchange could be caused by seasonal fluctuations or geothermal activity. Motivated by these real-world influences, we extend the theoretical framework presented in Panfilov (2021) to investigate the universal evolution of the temperature field in the cavity, insulation, and rock regions. This study will track the emergence, persistence (dependent on heat balance), and eventual disappearance of the ice zone while determining its maximum thickness as a function of various parameters. We anticipate that heat generation will accelerate heat transfer between zones, reducing the perturbation length and consequently shortening the lifespan of the ice ring. Conversely, heat absorption will slow down thermal wave propagation by increasing the perturbation time length, thereby prolonging the freezing front of the ice ring and extending the life of both the ice crust and the cryogenic liquid within the underground cavity.
{"title":"Prolonging the life time of underground ice ring formed in the period of the cryogenic gas storage","authors":"Mustafa Turkyilmazoglu , Abdulaziz Alotaibi","doi":"10.1016/j.euromechflu.2025.204395","DOIUrl":"10.1016/j.euromechflu.2025.204395","url":null,"abstract":"<div><div>Building upon a modified Karman–Pohlhausen technique, a recent study by Panfilov (2021) employed spherical coordinates to solve the heat transport problem in a heterogeneous domain surrounding a cavity storing cryogenic fluids underground. This analysis revealed the formation of an ice ring around the cavity, acting as a protective barrier against flooding from the stored material. This present work expands on that research by introducing heat generation and absorption into the media, aiming to analyze the temporal evolution of temperature and its impact on ice ring formation. Such heat exchange could be caused by seasonal fluctuations or geothermal activity. Motivated by these real-world influences, we extend the theoretical framework presented in Panfilov (2021) to investigate the universal evolution of the temperature field in the cavity, insulation, and rock regions. This study will track the emergence, persistence (dependent on heat balance), and eventual disappearance of the ice zone while determining its maximum thickness as a function of various parameters. We anticipate that heat generation will accelerate heat transfer between zones, reducing the perturbation length and consequently shortening the lifespan of the ice ring. Conversely, heat absorption will slow down thermal wave propagation by increasing the perturbation time length, thereby prolonging the freezing front of the ice ring and extending the life of both the ice crust and the cryogenic liquid within the underground cavity.</div></div>","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":"115 ","pages":"Article 204395"},"PeriodicalIF":2.5,"publicationDate":"2025-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145333165","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-14DOI: 10.1016/j.euromechflu.2025.204394
Erik Lindborg
In recent years, several studies have been made in which atmospheric and oceanic data were used to decompose horizontal velocity statistics into a rotational component, associated with vertical vorticity, and a divergent component, associated with horizontal divergence. The decomposition methods rely on the assumption of statistical isotropy. In this paper, the full anisotropic equations relating the rotational, divergent and the rotational-divergent components of the second order velocity structure function tensor to the longitudinal, transverse and longitudinal–transverse components are formulated and solved analytically.
{"title":"A complete Helmholtz decomposition of second order horizontal velocity structure functions","authors":"Erik Lindborg","doi":"10.1016/j.euromechflu.2025.204394","DOIUrl":"10.1016/j.euromechflu.2025.204394","url":null,"abstract":"<div><div>In recent years, several studies have been made in which atmospheric and oceanic data were used to decompose horizontal velocity statistics into a rotational component, associated with vertical vorticity, and a divergent component, associated with horizontal divergence. The decomposition methods rely on the assumption of statistical isotropy. In this paper, the full anisotropic equations relating the rotational, divergent and the rotational-divergent components of the second order velocity structure function tensor to the longitudinal, transverse and longitudinal–transverse components are formulated and solved analytically.</div></div>","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":"115 ","pages":"Article 204394"},"PeriodicalIF":2.5,"publicationDate":"2025-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145333164","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-11DOI: 10.1016/j.euromechflu.2025.204392
Wenhui Zhai , Yuxin Fan , Wei Wang
In advanced afterburner systems, a high inflow temperature can induce thermal autoignition of fuel, resulting in undesirable temperature distributions and causing ablation of flameholders and fuel injection devices. To explore the thermal autoignition characteristics of RP-3 aviation fuel, experiments were conducted using a pressure-swirl atomizer with a forward fuel supply. Key operating parameters included inflow velocity (50–150 m/s), inflow temperature (1000–1200 K), oxygen content (10.5 %–14.1 %), and fuel–air ratio (0.04–0.06). The results indicate that the thermal release and dissipation of autoignition reactions are key factors influencing the autoignition length and mode. Increasing the inflow temperature and fuel–air ratio promotes greater thermal release, while higher flow velocity leads to increased thermal dissipation. When the thermal release is low (e.g., at 1000 K) or thermal dissipation is high (e.g., at 150 m/s and 1100 K), the autoignition mode exhibits randomness, and the flame structure shows a single peak. In cases of low thermal release, an inflow velocity greater than 100 m/s inhibits thermal occurrence. Conversely, with high thermal release (e.g., at 1200 K) or low thermal dissipation (50–100 m/s and 1100 K), the autoignition mode transitions from random to continuous, and the flame structure changes from unimodal to bimodal. Keeping other conditions constant, increasing the inflow temperature from 1000 K to 1200 K reduces the autoignition length by 7.3 %–56.8 %. Similarly, increasing the fuel–air ratio from 0.04 to 0.06 decreases the autoignition length by 12.5 %–49.5 %. On the other hand, raising the inflow velocity from 50 m/s to 150 m/s increases the autoignition length by 32.9 %–252.0 %.
{"title":"Effects of high-velocity flow and oxygen-lean conditions on autoignition of RP-3 aviation fuel","authors":"Wenhui Zhai , Yuxin Fan , Wei Wang","doi":"10.1016/j.euromechflu.2025.204392","DOIUrl":"10.1016/j.euromechflu.2025.204392","url":null,"abstract":"<div><div>In advanced afterburner systems, a high inflow temperature can induce thermal autoignition of fuel, resulting in undesirable temperature distributions and causing ablation of flameholders and fuel injection devices. To explore the thermal autoignition characteristics of RP-3 aviation fuel, experiments were conducted using a pressure-swirl atomizer with a forward fuel supply. Key operating parameters included inflow velocity (50–150 m/s), inflow temperature (1000–1200 K), oxygen content (10.5 %–14.1 %), and fuel–air ratio (0.04–0.06). The results indicate that the thermal release and dissipation of autoignition reactions are key factors influencing the autoignition length and mode. Increasing the inflow temperature and fuel–air ratio promotes greater thermal release, while higher flow velocity leads to increased thermal dissipation. When the thermal release is low (e.g., at 1000 K) or thermal dissipation is high (e.g., at 150 m/s and 1100 K), the autoignition mode exhibits randomness, and the flame structure shows a single peak. In cases of low thermal release, an inflow velocity greater than 100 m/s inhibits thermal occurrence. Conversely, with high thermal release (e.g., at 1200 K) or low thermal dissipation (50–100 m/s and 1100 K), the autoignition mode transitions from random to continuous, and the flame structure changes from unimodal to bimodal. Keeping other conditions constant, increasing the inflow temperature from 1000 K to 1200 K reduces the autoignition length by 7.3 %–56.8 %. Similarly, increasing the fuel–air ratio from 0.04 to 0.06 decreases the autoignition length by 12.5 %–49.5 %. On the other hand, raising the inflow velocity from 50 m/s to 150 m/s increases the autoignition length by 32.9 %–252.0 %.</div></div>","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":"115 ","pages":"Article 204392"},"PeriodicalIF":2.5,"publicationDate":"2025-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145333163","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-11DOI: 10.1016/j.euromechflu.2025.204391
Zihao Zhao, Lingyun Tian, Xiaoyang Xu
This paper proposes an improved multi-resolution smooth particle hydrodynamics (SPH) method for efficiently and accurately simulating the free surface flow of viscous fluids. To address the numerical instabilities arising from interactions between coarse and fine particles due to differences in smoothing length, this study proposes a particle refinement method inspired by adaptive mesh refinement (AMR) and introduces a multi-layer background grid coupling mechanism to improve numerical accuracy while maintaining computational efficiency. To resolve physical field discontinuities at the interface between refined and non-refined regions due to the truncation of the smoothing kernel, buffer particles (including child guard and parent guard particles) are introduced on both sides of the refined region. The physical properties of hidden parent guard particles are updated by fine particles within the fine background grid, ensuring a smooth transition of physical quantities between coarse and fine particle regions. To mitigate tensile instability caused by irregular particle distribution, the particle shifting technique is further enhanced, improving the stability of multi-resolution simulations. Finally, comparisons with single-resolution simulations of dam-break flow, hydrostatic water column, and F-shaped cavity flow demonstrate that the proposed method significantly improves computational efficiency while maintaining high accuracy, thus confirming its effectiveness and robustness.
{"title":"An improved weakly compressible multi-resolution SPH method for free-surface flow simulation","authors":"Zihao Zhao, Lingyun Tian, Xiaoyang Xu","doi":"10.1016/j.euromechflu.2025.204391","DOIUrl":"10.1016/j.euromechflu.2025.204391","url":null,"abstract":"<div><div>This paper proposes an improved multi-resolution smooth particle hydrodynamics (SPH) method for efficiently and accurately simulating the free surface flow of viscous fluids. To address the numerical instabilities arising from interactions between coarse and fine particles due to differences in smoothing length, this study proposes a particle refinement method inspired by adaptive mesh refinement (AMR) and introduces a multi-layer background grid coupling mechanism to improve numerical accuracy while maintaining computational efficiency. To resolve physical field discontinuities at the interface between refined and non-refined regions due to the truncation of the smoothing kernel, buffer particles (including child guard and parent guard particles) are introduced on both sides of the refined region. The physical properties of hidden parent guard particles are updated by fine particles within the fine background grid, ensuring a smooth transition of physical quantities between coarse and fine particle regions. To mitigate tensile instability caused by irregular particle distribution, the particle shifting technique is further enhanced, improving the stability of multi-resolution simulations. Finally, comparisons with single-resolution simulations of dam-break flow, hydrostatic water column, and F-shaped cavity flow demonstrate that the proposed method significantly improves computational efficiency while maintaining high accuracy, thus confirming its effectiveness and robustness.</div></div>","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":"115 ","pages":"Article 204391"},"PeriodicalIF":2.5,"publicationDate":"2025-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145333159","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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